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Current Measurement with NI myRIO

This document shows two ways to measure current with an analog input for voltage.

  1. Current Measurement with Shunt Resistor
  2. Current Measurement with Hall-Effect-Based Current Sensor IC

Current Measurement Shunt.png


Resistance: 0.1 Ohm
Load Capacity: 10 W

Measured Voltage: 0.5 V

R = U / I

I = U / R
I = 0.5 V / 0.1 Ohm
I = 5 A

Maximum current  for Load Capacity 10 W:

P = I² * R

I = sqrt (P / R)

Imax = sqrt (10 W / 0.1 Ohm)

Imax = 10 A

LabVIEW Code:

AI Task for Current.PNG


Current Measurement with Hall.png

There are different Hall-Effect-Based Current ICs. This example shows a ACS712 from Allegro MicroSystems, Inc.

You can order the IC with breakout module or you can build your own board. In ACS712 datasheet is a circuit diagram. Search in web for ACS712 datasheet. AC712 deliver not the best results if you want to measure only some milliampere.

ACS712 consists of a linear Hall circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which the Hall IC converts into a proportional voltage.

This picture shows the ACS712ELCTR-20A-T with breakout module. ACS712ELCTR-20A-T has an optimized Range of +/- 20 A and a sensitivity of 100 mV/A.


Please note that there are different Hall-Effect-Based Current ICs with different ranges and sensitivities.

The LabVIEW code for the Hall-Effect-Based Current measurement is the same like for Shunt Resistor.
The scaling depends on the Hall-Effect Sensor type.


Hi Everyone!

I am using Ni cRio and 9201 module, and want to measure current using Allegro ACS 750. But unable to measure the same using LabView. Kindly help me building VI in Labview.